This invention relates to devices and methods for accurately and securely positioning the distal end of a catheter during a medical procedure. Specifically, devices and methods are provided for controlling the movement of the distal end of the catheter procedure while being used in a body lumen or organ cavity.
In many procedures utilizing catheters, one of the most difficult challenges is effectively navigating the catheter to its intended location and maintaining the distal end, or operating end of the catheter at the intended locations throughout the medical procedure. In cases where the catheter is placed through a narrow body lumen such as a blood vessel, maintaining the orientation of the distal end of the catheter within the lumen may be somewhat manageable. However, in applications where the body lumen is relatively large in comparison to the diameter of the catheter, or the catheter is delivered to a cavity of a body organ such as the left ventricle of the heart, the distal end of the catheter will likely have a greater range of movement and, thus, may be more difficult to position accurately.
Several procedures utilizing catheters percutaneously delivered to the ventricle of the heart have been disclosed. For example, various methods of treating ischemic myocardial tissue involve introducing a catheter into the ventricle of the heart. Creating channels in the heart tissue with a laser catheter is disclosed in U.S. Pat. No. 5,769,843 (Abella et al.) and U.S. Pat. Nos. 5,380,316 and 5,389,096 (Aita). The patents disclose utilizing laser energy discharged from the distal end of a catheter to ablate tissue from the heart wall to create a channel. U.S. Pat. No. 5,429,144 (Wilk) and International patent application publication no. WO 9849964 disclose delivering an implantable stent device into the heart wall from a catheter that has been percutaneously introduced into the ventricle of the heart. Stabilizing the distal end of such catheters during the given treatment procedure would appear to be critical.
It would be advantageous to provide a systemication of a compressive force delivered through a pull wire that extends through the catheter. The expansion of the flexible vanes increases the profile of the catheter at its distal end such that the vanes will contact interior wall surfaces of the body lumen or organ in which the catheter is placed thereby preventing unwanted movement of the catheter.
The present invention provides various mechanisms for positioning the distal end of a catheter at its intended treatment site within a patient. Two approaches to positioning the distal end of the catheter are disclosed. In a first embodiment, the distal end of the catheter employs a collapsible superstructure which causes the distal tip of the catheter mounted thereto to change direction so that the distal opening of the catheter can be directed to the intended tissue site. The superstructure is comprised of two flexible veins mounted along the side wall of the distal end of the catheter parallel to the longitudinal axis of the catheter that are biased to bow radially outward upon an application of a compressive force delivered through a pull wire that extends through the catheter. The expansion of the flexible veins increases the profile of the catheter at its distal end such that the veins will contact interior wall surfaces of the body lumen or organ in which the catheter is placed thereby preventing unwanted lateral movement of the catheter. The distal tip of the catheter is mounted to the distal end of one of the vanes so that the vane lies along the longitudinal axis of the catheter when the vanes are unstressed. Therefore, when the vanes are bowed radially outward the angular displacement of the vane at the connection point with the distal tip of the catheter, away from the longitudinal axis of the catheter, causes the distal tip to have a corresponding angular displacement. The variable angular displacement of the tip during displacement of the vanes provides a steering mechanism for the tip of the catheter so that it may be navigated to a particular tissue location.
In another aspect of the invention, the catheter positioning system comprises radially extending fingers at the distal end of the catheter which extend outward into surrounding tissue at the intended location to secure the catheter. The radially extending fingers remain retracted within the catheter during navigation to the intended treatment site and are extended to engage tissue upon reaching the treatment site. The number of radially extending fingers may vary depending on the retention force of the catheter necessary to perform the intended procedure. At least one of the fingers may be tubular, such as a hypotube. The tubular finger may be used to deliver a therapeutic agent to the tissue engaged by the finger. Additionally, the stiffness of the catheter shaft may be varied to help provide the desired directional stability of the catheter when restrained by the positioning system.
Various mechanisms for actuating the radially extending fingers may be employed. The fingers may be resiliently biased radially inward in the recessed position and forced into the extended position by another device advanced through the central lumen of the catheter. Alternatively, the fingers may be actuated by control cables extending along the length of the catheter either through a central lumen or through smaller independent lumens in the side wall of the catheter. The proximal ends of such cables can be joined to a handle mechanism joined to the proximal end of the catheter to facilitate actuation by a physician.
It is an object of the present invention to provide a system for effectively controlling the position of the distal end of a catheter that has been navigated to a treatment site in a patient.
It is another object of the invention to provide a catheter positioning system that operates to locate the distal end of the catheter and control the orientation of its distal tip by deforming an external superstructure joined to the distal end of the catheter.
It is another object of the invention to provide a catheter positioning system that operates to locate the distal end of a catheter by providing radially extending fingers that penetrate into adjacent tissue.
It is another object of the invention to provide a method for positioning the distal end of a catheter that comprises actuating a mechanical component at the distal end of the catheter to engage surrounding tissue.
It is another object of the invention to provide a catheter positioning system that is easy to use and economical to incorporate into a catheter design.